The altimeter profile should be selected when your outdoor activity involves changes in altitude (e.g. hiking in hilly terrain). The Barometer profile should be selected when your outdoor activity does not involve changes in altitude (e.g. surfing, sailing). To get the correct readings, you need to match the profile to the activity. You can either let Suunto Essential decide which profile is most suitable for you at the moment, or you can choose a suitable profile yourself.
To set the profile:
Alternatively you can set the profile in the Alti & Baro mode by keeping pressed down.
To set the reference value:
You’re hiking and take a break when you see a sign with the current altitude. You check your altitude reading and discover a small difference between the two numbers. You set the altitude reference value on your to match that of the sign.